package com.gglu.www.util;

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

/**
 * 杭州新苗网络科技有限公司
 *
 * @author meihf
 * @create 2018/1/28
 * @description
 */
public class WeixinConfigUtil {

        // 与接口配置信息中的Token要一致
        private static String token = "feng521Feng";


        public static boolean checkSignature(String signature, String timestamp,
                                             String nonce) {
            //从请求中（也就是微信服务器传过来的）拿到的token, timestamp, nonce
            String[] arr = new String[] { token, timestamp, nonce };
            // 将token、timestamp、nonce三个参数进行字典序排序
            sort(arr);
            StringBuilder content = new StringBuilder();
            for (int i = 0; i < arr.length; i++) {
                content.append(arr[i]);
            }
            MessageDigest md = null;
            String tmpStr = null;

            try {
                md = MessageDigest.getInstance("SHA-1");
                // 将三个参数字符串拼接成一个字符串进行sha1加密
                byte[] digest = md.digest(content.toString().getBytes());
                //将字节数组转成字符串
                tmpStr = byteToStr(digest);
            } catch (NoSuchAlgorithmException e) {
                e.printStackTrace();
            }

            content = null;
            // 将sha1加密后的字符串可与signature对比，标识该请求来源于微信
            return tmpStr != null ? tmpStr.equals(signature.toUpperCase()) : false;
        }

        //将加密后的字节数组变成字符串
        private static String byteToStr(byte[] byteArray) {
            String strDigest = "";
            for (int i = 0; i < byteArray.length; i++) {
                strDigest += byteToHexStr(byteArray[i]);
            }
            return strDigest;
        }

        private static String byteToHexStr(byte mByte) {
            char[] Digit = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A',
                    'B', 'C', 'D', 'E', 'F' };
            char[] tempArr = new char[2];
            tempArr[0] = Digit[(mByte >>> 4) & 0X0F];
            tempArr[1] = Digit[mByte & 0X0F];

            String s = new String(tempArr);
            return s;
        }
        //用于字典排序
        public static void sort(String a[]) {
            for (int i = 0; i < a.length - 1; i++) {
                for (int j = i + 1; j < a.length; j++) {
                    if (a[j].compareTo(a[i]) < 0) {
                        String temp = a[i];
                        a[i] = a[j];
                        a[j] = temp;
                    }
                }
            }
        }
}
